The Soviet Union in its first response to President Carter's Monday night Cuban speech accused him of gunboat diplomacy for stepping up American military forces and activity in the Caribbean to counter Soviet troops in Cuba.

The Soviet news agency Tass further charged that Carter in his speech to the nation "confirms that he and those around him intend to use the myth that they themselves created of a threat to the U.S. by Cuba and the Soviet Union" to step up the arms race and raise world tensions.

In its first retort to the president's address, Tass in a 1,000-word dispatch from Washington tonight complained that the United States, by planning "large-scale naval exercises" in the area, is trying to intimidate Latin America. "In other words, it is a question of a step-up of 'gunboat diplomacy' in the Caribbean."

Tass asserted that the president "distorted the character of Soviet-Cuban relations" when he said that massive Soviet economic and technical assistance to Havana since Fidel Castro came to power 20 years ago "is a manifestation of Moscow's dominance of Cuba."

The dispatch is considerably milder in tone than the agency's bitter personal attack on Carter last week, in which it accused him of using "an ultimatum-like, threatening tone" in his demands that the troops' status be changed. Tass maintained the Kremlin's position that the 2,500-3,000 Soviet troops in Cuba are military instructors, not a combat brigade as the administration asserts. "Jimmy Carter admitted that the U.S. does not face any immediate, concrete threat," it reported.

Seen from here, the Tass dispatch contains no real surprises, but does have clues about the attitude of the Kremlin, whose cautious, aging leaders are eager for Senate ratification of the strategic arms limitation treaty (SALT II) that Carter and Soviet leader Leonid Brezhnev signed in Vienna in June. The treaty has been stalled in the Senate since the troop issue surfaced a month ago.

Tass quoted verbatim from Carter's Monday night warning to a nation-wide television and radio audience that the treaty must not become a political football. Senior Soviet advisers in private conversations and interviews here in the past week have made clear that while the Kremlin has no intention of withdrawing the troops or altering their status in any way, it also has bedrock hopes that SALT II will be ratified.

By picking up the old theme of American "gunboat diplomacy," the Tass agency set a tone sure to find acceptance in Havana, where the volatile Castro has bitterly denounced the U.S. in recent weeks. Today, Cuban media reported in detail Carter's speech without comment.

However, with Brezhnev said to be prepared to deliver a major foreign policy speech from East Berlin Saturday, it is likely that the Kremlin has more to say about the Cuban dispute and the role of the United States in world affairs.